02 Chemistry of Life
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Essentials of Anatomy & Physiology
Title: Essentials of Anatomy & Physiology
Edition: 4th Edition Martini / Bartholomew
Prepared by: Alan Magid, Duke University
Focus: The Chemical Level of Organization
Slides: 1 to 74
Copyright: 2007 Pearson Education, Inc.
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Matter: Atoms and Molecules
Atoms: Smallest unit of an element.
Subatomic Particles:
Protons: Positive charge (+)
Neutrons: Neutral charge
Electrons: Negative charge (-)
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Structure of an Atom
Nucleus: Contains protons and neutrons.
Electron Shell: Region around nucleus where electrons are found.
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Structure of an Atom (Continued)
Atomic Number: Equals the number of protons.
Atomic Mass: Equals protons + neutrons.
Isotopes: Variants of an element that have different numbers of neutrons.
Atomic Weight: Average of isotope abundances.
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Electrons and Their Role
Electrons surround the nucleus.
Organized in shells; the outer shell determines chemical properties.
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Atoms and Electron Shells
Carbon Atom: (6 protons, 6 neutrons, 6 electrons)
Neon Atom: (10 protons, 10 neutrons, 10 electrons)
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Key Note on Atoms
All matter is composed of atoms in various combinations, foundational to physiology at the cellular level.
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Chemical Bonds and Compounds
Atoms bond during chemical reactions, transferring electrons.
Molecules or compounds form as a result of these reactions.
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Ionic Bonds
Atoms gain or lose electrons, becoming charged ions.
Cations: Positively charged ions.
Anions: Negatively charged ions.
Opposite charges attract, forming bonds.
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Formation of Ionic Bonds - Example
Formation of ions: Sodium atom loses an electron to become Na+.
Attraction between Na+ and Cl- leads to ionic compound formation.
Resulting compound: Sodium chloride (NaCl).
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Sodium Chloride Crystal
Visual representation of a sodium chloride crystal with chloride ions (Cl-) and sodium ions (Na+).
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Common Ions in Body Fluids
Cations:
Na+ (sodium)
K+ (potassium)
Ca2+ (calcium)
Mg2+ (magnesium)
Anions:
Cl- (chloride)
HCO3- (bicarbonate)
HPO4^2- (biphosphate)
SO4^2- (sulfate)
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Covalent Bonds
Atoms sharing electrons to complete their outer shell.
Single Covalent Bond: One pair of shared electrons.
Double Covalent Bond: Two pairs of shared electrons.
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Covalent Bonds - Models
Electron-Shell Model: Illustrations of common molecules (e.g., H2, O2, CO2).
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Nonpolar and Polar Covalent Bonds
Nonpolar Covalent Bonds: Equal sharing of electrons (e.g., carbon-carbon).
Polar Covalent Bonds: Unequal sharing of electrons (e.g., oxygen-hydrogen).
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Hydrogen Bonds
Weak attractive forces between neighboring atoms (e.g., polar-bonded hydrogen and polar-bonded oxygen or nitrogen).
Example: Hydrogen bonds in water molecules.
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Visual Representation of Hydrogen Bonds
Illustrations showing hydrogen bonding between water molecules.
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Chemical Notation
Simplified descriptions of compounds, structures, reactions, and ions using chemical shorthand.
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Chemical Reactions and Metabolism
All metabolic reactions in body consume reactants and produce products.
These reactions involve breaking or making chemical bonds.
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Basic Energy Concepts
Work: Movement or change in matter’s physical structure.
Energy: Ability to do work, categorized as kinetic or potential.
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Energy Types
Potential Energy: Stored energy (e.g., a leopard in a tree).
Kinetic Energy: Energy of movement (e.g., a leopard pouncing).
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Types of Chemical Reactions
Decomposition: Breaks molecules into smaller pieces.
Synthesis: Assembles smaller pieces into larger ones.
Exchange: Shuffles pieces between molecules.
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Decomposition Reactions
Chemical notation: AB ➔ A + B.
Releases covalent bond energy; includes hydrolysis.
Catabolism: Sum of all body’s decomposition reactions.
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Synthesis Reactions
Chemical notation: A + B ➔ AB.
Absorbs energy; forms new bonds.
Dehydration Synthesis: Removal of H2O between molecules.
Anabolism: Sum of synthesis reactions in the body.
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Exchange Reactions
Chemical notation: AB + CD ➔ AC + BD.
Involves both decomposition and synthesis.
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Reversible Reactions
Notation: A + B ⇌ AB.
Equilibrium: Condition where forward and reverse reactions happen at the same rate.
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Key Note on Energy Exchange
Energy exchange produces heat, raising local temperatures, but cells cannot capture it for work.
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Enzymes and Reactions
Activation Energy: Energy needed to start a chemical reaction.
Catalysts: Substances that lower activation energy, speeding reactions.
Enzymes: Biological catalysts for cellular reactions.
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Enzyme Activation Energy
Visual representation of reaction progress with and without enzyme catalysis.
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Types of Reactions: Energy Release/Consumption
Exergonic: Reactions that release energy (e.g., decomposition).
Endergonic: Reactions that consume energy (e.g., synthesis).
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Inorganic Compounds
Nutrients: Essential elements/molecules obtained from diet.
Metabolites: Molecules synthesized or broken down by chemical reactions in the body.
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Characteristics of Inorganic Compounds
Inorganic: Smaller molecules lacking carbon and hydrogen (e.g., water, oxygen).
Organic: Larger molecules rich in carbon and hydrogen (e.g., sugars, proteins, fats).
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Inorganic Gases
Carbon Dioxide (CO2): Gas produced by metabolism and released via lungs.
Oxygen (O2): Atmospheric gas consumed by cells to produce energy.
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Water Properties
Importance: Most significant body chemical.
Functions: Excellent solvent, high heat capacity, and essential reactant in biological reactions.
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Water and Ionic Bonds Dissociation
Water molecules can dissociate ionic bonds, illustrated by sodium chloride in solution.
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Key Note on Water
Water accounts for a significant portion of body weight and is crucial for proteins and nucleic acids to function properly.
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Inorganic Acids and Bases
Acid: Releases H+ into solution (e.g., HCl ➔ H+ + Cl-).
Base: Removes H+ from solution (e.g., NaOH + H+ ➔ Na+ + OH-).
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pH Measurement
Definition: Measure of H+ concentration in a solution.
Neutral solution: pH = 7.
Acidic solution: pH < 7.
Basic solution: pH > 7.
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pH and Concentration of Ions
Illustrates various solutions and their corresponding pH levels, highlighting acidic, neutral, and basic examples.
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Buffers
Maintain pH within normal limits (pH 7.35 to 7.45).
Release H+ if fluid is too basic; absorb H+ if too acidic.
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Salt and Electrolytes
Salt: Ionic compound not containing H+ or OH-.
Electrolytes: Dissociate in water (e.g., NaCl ➔ Na+ + Cl-), important for carrying electrical currents in the body.
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Organic Compounds Characteristics
Composition: Contain carbon, hydrogen, and usually oxygen.
Major classes: Carbohydrates, Lipids, Proteins, Nucleic acids.
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Carbohydrates
Function: Primary energy source for metabolism.
Types:
Monosaccharides (e.g., glucose)
Disaccharides (e.g., sucrose)
Polysaccharides (e.g., glycogen).
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Structure of Glucose
Chemical structure representation of glucose molecule.
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Formation and Breakdown of Complex Sugars
Dehydration Synthesis: Joining two molecules by removing a water molecule.
Hydrolysis: Breaking down complex molecules by adding water.
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Formation of Glycogen
Glucose molecules chemically combine to form glycogen.
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Table of Carbohydrates in the Body
Types and Functions:
Monosaccharides: e.g., glucose, fructose - energy source.
Disaccharides: e.g., sucrose, lactose - energy source.
Polysaccharides: e.g., glycogen - storage of glucose.
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Overview of Lipids
Characteristics: Water-insoluble molecules.
Classes:
Fatty Acids
Fats
Steroids
Phospholipids.
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Representative Lipids and Their Functions
Lipid Type | Examples | Primary Functions |
|---|---|---|
Fatty Acids | Lauric acid | Energy source |
Fats | Monoglycerides, etc. | Energy source, storage, insulation |
Steroids | Cholesterol | Hormones, cell membrane component |
Phospholipids | Lecithin | Membrane structure |
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Fatty Acids Structure
Represents Lauric acid (C12H24O2).
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Triglycerides
Formed by three fatty acids bonding to a glycerol molecule.
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Cholesterol Functions
Building block for steroid hormones and component of cell membranes.
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Phospholipids
Most abundant membrane lipid: contains two fatty acids and glycerol with both water-soluble and insoluble parts.
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Structure of a Phospholipid
Illustration showing molecular components of a phospholipid.
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Proteins
Most abundant organic component in the human body, composed of carbon, nitrogen, oxygen, hydrogen, and sulfur.
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Vital Roles of Proteins
Functions:
Support, Movement, Transport, Buffering, Regulation, Defense.
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Amino Acids
Structure of an amino acid including central carbon, amino group, carboxylic acid, and "R" group.
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Peptide Bonds
Peptide bonds formed through dehydration synthesis; breakdown via hydrolysis.
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Protein Structure
Describes polypeptide chains and their folding into complex shapes affecting function.
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Enzyme Function
Enzymes lower activation energy, allowing substrates to bind and convert to products.
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Steps of Enzyme Action
Substrates bind to the enzyme's active site.
Substrates interact to form products.
Products detach, allowing the enzyme to repeat the process.
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Nucleic Acids
Large molecules made of C, H, O, N, and P; responsible for storing and processing molecular information.
Types: DNA and RNA.
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Structure of Nucleic Acids
Composed of nucleotides with sugar, phosphate group, and nitrogenous base.
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Nucleotide Components
Visual representation including sugar, phosphate groups, and nitrogenous bases (A, T, C, G for DNA; U for RNA).
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Nucleic Acids Structure - Continued
Visual representation of hydrogen bonding in DNA structure.
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Nucleic Acids Structure Summary
Nucleotides linked by sugar-phosphate bonds, stabilize DNA strands with hydrogen bonds.
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High-Energy Compounds
Catabolism releases energy, stored in high-energy compounds (e.g., ATP) essential for cellular functions.
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Structure of ATP
ATP composed of adenine, ribose, and three phosphate groups, and plays a crucial role in energy transfer.
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Energy from Catabolism
Visual representation of energy transfer during ATP utilization.
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Energy Release Visuals
ATP to ADP/AMP energy cycle depicted.
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Summary of Energy from Cellular Catabolism
Illustrating continuous energy release for cellular activities.
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ATP Energy Release Processes
Explanation of ATP's role in energy release for maintaining cell function.
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Summary of ATP Energy Dynamics
Continuous cycle of energy from ATP for cellular activities.
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Summary of Body Chemistry
Overview of organic chemical building blocks in the body, highlighting various organic compounds and their roles:
Carbohydrates: Monosaccharides, Disaccharides, Polysaccharides.
Lipids: Triglycerides.
Proteins: Peptides.
Nucleic Acids: RNA, DNA.
High-Energy Compounds: ATP, composed of nucleotides.